Solve for $x$ : $x^2 + 6x + 9 = 0$
Explanation: The coefficient on the $x$ term is $6$ and the constant term is $9$ , so we need to find two numbers that add up to $6$ and multiply to $9$ The number $3$ used twice satisfies both conditions: $ {3} + {3} = {6} $ $ {3} \times {3} = {9} $ So $(x + {3})^2 = 0$ $x + 3 = 0$ Thus, $x = -3$ is the solution.